1. Field of the Invention
The present invention relates to electronic equipment having a cooling device circulating a cooling fluid.
2. Description of the Related Art
Electronic equipment includes mainframe computers and medium-scale server computers used by corporates such as banks, in addition to widely used personal computers and desk-top computers.
Server computers as electronic equipment are typically connected to a plurality of terminals. Such electronic equipment is formed of a plurality of stacked electronic devices, which run software programs for calculation or retrieving mail data.
Depending on the purposes of applications, the user must replace, add, or remove the electronic devices, each running the software program of its own.
The electronic equipment must be continuously powered 24 hours a day because the electronic equipment is constantly accessed by any of the terminals.
Each electronic device typically includes a sub-cooling unit in addition to a main-cooling unit. In the case of a failure of the main-cooling unit, an alarm alerting the user to the failure is triggered. The sub-cooling unit cools the electronic device until the main-cooling unit is restored.
Such cooling devices of the electronic equipment typically employ fans.
In step with the latest high processing speed and large memory capacity, semiconductor devices such as central processing units (CPUs) rise high in temperature to the degree with which a cooling device using a fan has difficulty. If cooling efficiency is increased, a noise problem due to high speed rotation of the fan arises. The cooling device using a cooling fluid circulation, once used in the mainframe computer field, is now reviewed.
Under these situations, a cooling device of the conventional art using a cooling fluid circulation is now studied from safety and reliability considerations.
For example, Japanese Unexamined Patent Application Publication No. 6-97338 discloses a fluid circulating type cooling device of a mainframe computer. In the disclosure, many wiring boards, each having a semiconductor device generating heat, are stacked in a casing of electronic equipment. A flat header is attached to the semiconductor. A cooling fluid is circulated in a flexible tube routed between the heat generator and a heat exchanger, thereby cooling the heat generator.
Japanese Unexamined Patent Application Publication No. 5-142886 discloses a notebook computer having a cooling device using a cooling fluid circulation. In the disclosure, a highly reliable and high-performance cooling device is used for a mobile electronic apparatus such as a notebook computer. A flexible heat transport device having a heat receiving header, a heat dissipating header, and a flexible tube is used in the cooling device.
In accordance with the conventional art described in the above disclosures, a cooling fluid, running through a flexible tube routed on a wiring board having heat generating electronic components, circulates between heat generating elements and a heat exchanger. No sufficient consideration is given to the loading and unloading of the wiring board.
When a wiring board having heat generating electronic components is loaded in a casing of electronic equipment, thermal coupling to a heat sink path (a cooling fluid piping) of the heat generating electronic components must be easily established in addition to electrical connection. There is no mention of such a structure satisfying this requirement in the above disclosures. The server in a network system has difficulty in the removal of a wiring board in need of replacement and the loading of another wiring board with safety in the casing particularly in the middle of operation of the electronic apparatus. In such electronic equipment, a new electronic module as a wiring board having heat generating electronic components must be occasionally added.
If a wiring board mounted in the electronic apparatus or a component in a cooling fluid circulation system fails, the wiring board or the component must be replaced. However, the above conventional arts provide no mechanism appropriate for allowing a corrective action to take without stopping the operation of the system.
If the fluid circulation type cooling device is attached to each electronic apparatus, the cooling device may be duplicated, such as a safety mechanism using a fan.
The duplication of the fluid circulation type cooling device in each electronic apparatus raises space and cost problems.
Accordingly, it is an object of the present invention to provide reliable electronic equipment that is free from the above mentioned problem.
It is another object of the present to provide electronic equipment which has a cooling structure that allows electronic modules to be added or maintained, a structure of a casing of the electronic equipment, and such an electronic module appropriate for the structure of the casing.
The present invention relates to electronic equipment, and includes a plurality of electronic apparatuses, each electronic apparatus having a semiconductor element, a rack for storing the plurality of electronic apparatuses stacked with one above another, a first cooling device, in the electronic apparatus, including a first heat receiver for receiving heat from the semiconductor element, a first fluid circulator for circulating a fluid through the first heat receiver, a first heat exchanger for discharging heat of the fluid, and a first piping for connecting the first heat receiver, the first fluid circulator, and the first heat exchanger, and a second cooling device, in the rack, including a second heat receiver in contact with the first heat receiver, a second fluid circulator for circulating the fluid through the second heat receiver, a second heat exchanger in contact with the second heat receiver, and a second piping for connecting the second heat receiver, the second fluid circulator, and the second heat exchanger.
Preferably, the first cooling device is detachably mounted on the rack, and the second piping includes a switching valve for switching the supplying of the fluid to the second cooling device when the first cooling device is mounted to or demounted from the rack.
Preferably, the direction of circulation of the fluid circulating in the first cooling device is different from the direction of circulation of the fluid circulating in the second cooling device.
Preferably, the diameter of the second piping becomes smaller from upstream to downstream in the circulation of the fluid.
FIG. 1 is a perspective view of electronic equipment of one preferred embodiment of the present invention;
FIG. 2 is a sectional side elevation view of the electronic equipment of FIG. 1;
FIG. 3 is a sectional side elevation view of the electronic equipment with a single electronic apparatus removed;
FIG. 4 is a sectional side elevation view of the electronic equipment with the cross-sectional area of the passage of a piping changed;
FIG. 5 is a perspective view of an electronic apparatus implementing another preferred embodiment of the present invention;
FIG. 6 is a sectional side elevation view of the electronic apparatus of FIG. 5;
FIG. 7 is a sectional side elevation view of a single electronic apparatus which implements another preferred embodiment of the present invention;
FIG. 8 is a graph plotting the temperature of a CPU of the electronic apparatus of FIG. 7;
FIG. 9 is a top view illustrating the detail of an internal structure of the electronic equipment of another preferred embodiment of the present invention;
FIG. 10 is a sectional view illustrating the detail of an internal structure of a cooling jacket and a header in the electronic equipment;
FIG. 11 is a perspective view showing the structure of a fluid connector of the cooling jacket and the header in the electronic apparatus, partly broken away to reveal the interior thereof;
FIG. 12 illustrates a modification of a fluid circulation loop in the electronic equipment;
FIG. 13 illustrates the operational principle of the fluid circulation loop of FIG. 12;
FIG. 14 is a top view of a modification of the electronic apparatus;
FIG. 15A is a side view of the electronic equipment of another modification, FIG. 15B is a top view of the electronic equipment, and FIG. 15C is a sectional view of the electronic equipment taken along line Axe2x80x94A in FIG. 15B;
FIG. 16 illustrates a water-cooled wiring board of the electronic apparatus of FIG. 7 in a partly cross section;
FIG. 17 is a sectional view illustrating the internal structure of the cooling jacket of the electronic apparatus of FIG. 7;
FIG. 18 is a top view illustrating in detail the internal structure of the electronic equipment in accordance with another embodiment of the present invention;
FIG. 19 is an enlarged view illustrating a thermal coupling unit in each wiring board in the electronic equipment of the embodiment;
FIG. 20 is a top view of a contact structure between a water-cooled plate and a heat conductor shown in FIGS. 18 and 19;
FIGS. 21A and 21B are a side view and a top view of another contact structure between the water-cooled plate and the heat transfer plate shown in FIGS. 18 and 19; and
FIG. 22 is a top view illustrating a modification of the electronic equipment shown in FIG. 18.